Then and Now
As recently as the 1960’s, what we now
call Austin was predominantly undeveloped. The population was
186,545, a mere 28% of its size today. Most of our urban creeks
had a constant supply of water that provided an attractive escape
from city life along our plentiful hike and bike trails.
But we have found that as we change the land,
we change our creeks. A stroll along the moderately developed
Bull Creek today is vastly different from one along the fully
urbanized Shoal. It offers a comparison between a more naturally
vegetated watershed with cascading waterfalls versus an eroded
stream channel that goes from dry to flooded in a dangerously
short period of time.
Much of the change is caused by impervious cover,
the buildings and roadways that prevent water from filtering through
the soil to our groundwater. Groundwater feeds our creeks and
provides the baseflow that creates constantly flowing streams.
Besides the aesthetic appeal of a water-filled creek, this constant
flow provides a good habitat for fish and other aquatic species.
In the older, more established areas, impervious
cover prevents saturation into the land and rainwater flows very
quickly to storm drains. The rainwater carries pollutants in its
path to our creeks without being treated. The increased speed
of the water rushing to the stream channel causes flooding and
erosion that wipes out vegetation and habitat. When the flooding
conditions end, the creek then quickly dries since it is no longer
fed by groundwater. During storms, the stream is now a violent
and expensive threat to our neighborhoods, but when dry, they
become an unappealing “drainage ditch”.
Our challenge today is to better plan our growth
so that we can protect our natural heritage for us and our children.
Additional Information
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